Transmission rail lock



Feb. 24,1942.- 0. E. FISIHBURN 2,274,539

TRANSMISSION RAIL LbcK Filed Jan; 18, 1940 3 Sheets-Sheet 1 0220 E's/yam M M, 4; 9LM

ATTORNEY$- Feb. 24, 1942. E, I HBURN 2,274,539

ATTORNEYS.

Feb. 24, 1942.

O. E. FISHBURN TRANSMISSION RAIL LOCK I Filed Jan. l8, 1940 I5 Sheets-Sheet 3 42 INVENTOR ATTORNEY Patented Feb. 24, 1942 TRANSMIS SION RAIL LOCK Otto E. Fishburn, Detroit, Mich, assignor to Chrysler Corporation, Highland Park, Mich, a corporation of Delaware Application January 18, 1940, Serial"Nc. 314,531

1 Claim.

This invention relates to improvements in vari- I able speed transmission mechanism.

More particularly, the invention pertains to improved gear shifting control apparatus for "transmissions of this kind which is particularly adapted for use in motor vehicles.

The principal object of the invention is to prozvide in a variable speed transmission mechanism having shiftable members, a lock for at least one of said members which Will retain the member in neutral position except when it is desired to shift the same.

An additional object is to provide a locking device of the character indicated which is auto- "matic in operation and which will not interfere "with normal operation of the transmission.

A still further object is to provide such a looking device which is easy and economical to manufacture and which will not'require servicing after it is once assembled in the transmission casing.

Additional objects and advantages of the in- -vention'wil1 be apparent from the following description.

In the drawings which illustrate a preferred embodiment of my invention,

Fig. 1 is a plan view. partially in section, of a itransm'ission embodying my invention.

Fig. 'Z'is a sectional view along line 2-4. of Fig. 1.

' Fig. '3 is a sectional view along line '3-3 of Fig. 2.

Fig. *4 is a sectional view along line 4-4 of Fig. 1.

Fig. 5 is a sectional view taken approximatelyalong line '5'5 of Fig. 2.

Fig. '6 is a sectional view along line 5-45 of Fig. 2.

The drawings illustrate an embodiment of the invention which is intended to be used in amotor vehicle having the usual engine and clutch (not shown).

The'transmission it includes a housing l5 into which extends a driving shaft it having a gear 'l 'lmeshed with a gear it fixed on a ncountershaft and El respectively.-

Splined on the shaft It is a hub member having teeth 26'. A shiftable clutch member 23 is splined on the hub member at a location between the hub portion of the gears ill and 2D and provided with internal'clutch teeth with which the clutch teeth 2? audit respectively are adapted to be selectively meshed as is well known in the art. A direct drive setting of the gears may be produced by shifting the clutch member 23 to the'lefhas viewedin Figs. 1 and 4, to connect the clutch teeth 26 with "the teeth 26'. When the clutch member '23 is shifted to the right the-teeth 21 and 26 are connected thereby holding the gear 2i! against rotation relative to the shaft M. The gear 20 is permanently meshed with a gear 28 on the countershaft 19 by which the gear 20 and shaft M are driven to establish a second speed drive. Low speed and reverse settings of the transmission may be established by shifting the gear 2! into mesh with a gear 29 on the countersha'ft l9 and with a reversegear 3i driven by a pinion 3%) on the countershaft respectively.

A pair of shifter rails 35 and 3 8 extending longitudinally of the transmission at one "side thereof are shiftably mounted in bosses 35 and '36 of the housing I5. A pair of laterally extending shifter forks 38 and 39 :are slidably mounted on a rod 33 fixed in the housing at each end thereof, and respectively engage the grooves of the shift collars 23 and :22 as illustrated. A

fork 38 is :provided with a pair of spaced lugs M and M between which is receivable a rail shifting or selector finger 48, which also has apart which is receivable into a notch 4! in'the fork 39.

:bottom wall portions extending longitudinally .of

the transmission in whichare formed registering openings 44 and 45.

A shaft 42 extending vertically of the cover 3.1 is journ alled at its ends in the openings 44, 45. The shaft 42 has an external end portion protruding from the cover member 31 on which a lever 43 is non-'rotatably fixed. A collar 46 is .dispsoed within the cover and axially slidably mounted on the intermediate portion of the shaft 42 which is provided with flats 4'! for holding the collar and shaft against relative rotation. The collar 46 carries the rail shifting finger 48, heretofore referred to, which is provided with an intermediate lobe portion 49 that registers with and is adapted to be received by the notch 4| of the rail 36, and a lobe portion 56 that registers with and is receivable between the lugs 4|, 4| 6 of the shifter fork 38. A coil spring bears between a washer 5| which in turn bears against the upper rounded part of the shaft 42, and the bottom of a cup-shaped member 62' which rests on the enlarged portion of the collar 46 as shown in Figs. 2 and 6, for normally yieldably urging the collar 66 downwardly so as to retain the rail shifting finger 48 in operative engagement with the ,rail 36 and its shifter fork 38. The collar 46 may be moved upwardly, as viewed in Figs. 1 and 2,'to bring the end lobe 56 between the lugs 4|, M carried by the rail 35 and shifter fork 39.

The mechanism for moving the collar 66 upwardly against the pressure of the spring 5| is illustrated in Figs. 1, 4 and 6. The cover 3'! has a transversely extending boss 66 in which is rotatably mounted a shaft 6| having a flattened inner end 62 on which is mounted a fork 63. The latter has a pair of rounded end portions 64 which engage the underside of the enlarged portion of the collar 46 at each side thereof. A lever 65 (Figs. 1 and 4) non-rotatably carried on the outer end of the shaft 6| is adapted to be actuated by any suitable means which is under the control of the vehicle driver.

The apparatus for actuating the selector lever 65 and the shift lever 43 is preferably of the type illustrated in the co-pending application of Frederic W. Slack, Serial No. 293,657, filed September 7, 1939, but any other suitable apparatus may be employed if desired.

From the mechanism so far described, it may be readily understood that rocking of the shaft 6| against the spring 5| by means of the lever 65 will move the collar 46 and finger 46 upwardly thereby disengaging the latter from engagement with lugs 4|, 4| of rail 36 and engaging it with the notch 4 of rail 35.

Rocking of the shaft 42, with the finger 48 in its upper position, will slide the gear 2| forwardly into mesh with low speed drive gear 29 or rearwardly into mesh with reverse idler 3| as desired. When the finger 66 is in its lower position, rocking of the shaft 42 will slide clutch member 23 rearwardly to drivingly connect the teeth 26' with teeth 2'! of second speed gear 26, or forwardly to drivingly connect the teeth 26' with teeth 26 of shaft I6 as desired.

The rails 35, 36 are respectively provided with slots 66 which are adapted to receive the respective balls 61 of a pair of detents generally designated 66, 68'. The detent 68 is provided with the usual spring (not shown) for urging its respective ball into engagement with the second direct rail 36, it being understood that the ball is adapted to recede slightly against the spring when the rail 36 is shifted and to engage the respective slots 66 therein for retaining the rail in its various shift positions as is common in the art.

The detent 68' which is operatively associated with the low-reverse rail 35 differs from the conventional detent 68 in that it is provided with a control which under certain conditions locks the rail 35 against movement. As may be seen in Fig. 1 taken together with Figs. 2 and 4-6, the

- of a bolt 13 and has an inner rounded end 14 which engages the underside of a flange 15 formed on the cup-shaped member 42 as illustrated.

The lever 12 is so mounted with relation to the other parts that, when the collar 46 is in its lower position, which is the position to which it is normally retained by the spring 5|, the end ll of said lever is engaged with the reduced portion H of the plunger 10 as shown in Figs. 1 and 6. With the parts in this position, movement of the rail 35 is impossible because the plunger 76 prevents the detent ball 67 from movement. The rail 35 is thus locked in neutral position and the rail 36 is free to be shifted by the finger 48.

When the selector lever 65 is operated to move the finger 46 out of engagement with the rail 36 (where it is normally positioned by the spring 5|) and into engagement with the rail 35, as for instance, when shifting in low or reverse, upward movement of the collar 46 automatically unlocks the rail 35 because the upper surface of said collar contacts the rounded end 14 of lever l2 and rotates the lever about the bolt 13 thereby moving the end H of said lever out of engagement with the plunger 16. The rail 35 is thus freed for shifting, the plunger 10 moving inwardly against the spring 69 as the high portions of the rail 35 between the slots 66 contact ball 61.

An interlock pin 86 (Fig. 5) is also provided, this pin being adapted to engage either of the slots 8| provided in the shift rails according to which of the rails is shifted. The pin 86 may be eliminated if desired, but is preferably included for the purpose of locking the rail 36 in neutral during shifting of the rail 35.

In describing the operation of the device, let it be assumed that the vehicle in which the above described transmission mechanism is incoporated is provided with a suitable manually operated shift member which is oscillatable in a pair of transversely connected paths for shifting the transmission gears. With the transmission elements in neutral position as shown in the drawings, the selector or shift finger 48 will be urged by spring 5| into engagement with the lugs 6|, ll of high-second shift rail 36. Under such conditions the detent control arm 12 will be in the position shown in Fig. 6 With the rounded end 1| thereof in engagement with the reduced portion 1| of the detent control plunger 16 thereby locking the plunger and the ball 61 against movement which, in turn, locks the rail 35 against movement because of the engagement of the ball 6! with the centrally located recess 66 of said rail.

When shifting into low speed driving ratio, the driver, by suitable manipulation of the manually actuated shift lever (not shown) rotates selector lever 65 in a clockwise direction as shown in Fig. 1 which, through the intermediary of the fork 63, moves the collar 66 and selector finger 68 upwardly compressing the spring 5| and engaging the lobe 56 of said selector finger with the notch 4| of the low-reverse rail 35. As the collar 66 moves upwardly, it contacts the rounded end 14 of the detent control arm 12 swinging by lug 4|. finger 48 with lug 41*, the spring 5| will snap the same about the pivot 13 in a counterclockwise direction as viewed in Fig. 6 and moving the rounded end 1| out of engagement with the detent control plunger thereby freeing said plunger for sliding movement in the bore of deshaft gear 29.

When shifting from low speed into second or intermediate speed ratio, the lever 43 is manipulated to rotate shaft 42 in a clockwise direction as viewed in Fig. l to thereby slide gear 2| to the rightas viewed in Fig. 3 and out of mesh with gear 29. As the finger 48 which is in engagement with the notch 4| is traversed from left to right as viewed in Fig. 5, the lower right hand edge of said finger will engage the lug 4P when the parts reach neutral position because of the fact that the lug 4! is shorter than the lug 4P and therefore the finger 48 is held in engagement with the notch 4| during the shift from low to neutral against the force of spring At the instant of engagement of the collar 45 and finger 48 downwardly into engagement with the rail 36 at the same time swinging arm 12in a counterclockwise direction (as viewed in Fig. 6) to engage the end H thereof with the plunger 10 therebylocking rail 35. The finger 48may then continue its travel toward the right hand side of Fig. 5 to thereby move rail 36 toward the right and engage clutch member 23Iwith the teeth 21 formed on gear 2!]. Second or intermediate speed ratio drive will then have been established.

It will be appreciated that the above described movements may be accomplished by the vehicle driver in an extremely short space of time by a single movement of the manually actuated shift lever in one of its paths of shifting movement, it not being necessary for the driver to hold the collar 46 in its upper position against the force of spring 5| due to the fact that the finger 48 over is obtained at'the instant that the rail 35 reaches neutral position at which instant the finger 48 drops out of engagement with rail 35 and picks up rail 36 for the shift into second speed ratio. This shift from low to secondspeed may be accomplished as rapidly as desired with perfect safety and with no clashing ofgears due to overtravel of the rail 35 because rail 35 is locked in neutral position simultaneously with the crossover movement of finger 48 to pick up the rail 35.

If desired, the right hand side of the notch 4| may be chamfered slightly as shown in Fig. 5 to reduce the friction and give a quick release of thefinger 48. It may thus be seen that I have provided What may b termed a controlled detent which in addition to serving the function of conventional detents known to the prior art also functions as a controlled lock .for locking the low-reverse rail in neutral position during shifting of the second-high rail thereby permitting the advantages of the automatic cross-over V pects, the scope thereof being defined in the claim appended hereto and made a part hereof.

I claim:

In a change speed transmission mechanism having a housing and a pair of shift rails mounted in said housing for shifting longitudinally thereof, an opening in the side of said housing;

a cover for said opening; a rockshaft mounted vertically in said cover and having a portion extending outwardly thereof for engagement by a shift lever; a selector element carried by'said rockshaft and adapted for movement relatively thereto to selectively o'perably engage the rockshaft with said rails; detent means yieldably engaging said rails; a locking lever carried by said cover for rocking about an axis disposed perpendicular to the axis of said rockshaft; the ends of said locking lever being respectively disposed in engagement with said selector member and one of said detent means whereby shift of one of the rails is prevented while the selector member is in engagement with the other rail; and means for moving said selector member into engagement with said on rail including means for simultaneously rocking said locking lever to unlock said rail.

OTTO E. FISHBURN. 

